The historical background of the Sunni-Shi'i conflict -- The challenge of Shi'i conversion activity to Ottoman control of Iraq -- From subjecthood to citizenship -- The impact of the marriage prohibition on the rights and responsibilities of citizens -- Continuity and challenges to the prohibition of marriages during the last years of the Ottoman Empire and the first years of the Turkish Republic -- Conclusion -- Appendix A: Law of Ottoman nationality of 19 January 1869 -- Appendix B: 26 may 1914 "Draft law concerning the prohibition of marriages between Ottoman women and Iranian men" -- Appendix C: Law of 26 april 1926 "Concerning the Preservation of the Prohibition of Marriage Between Iranian and Turkish Citizens".